To be determined but in the current design you can fit up to 9mm thick drive in the front if you use a GPU shorter than 176mm. The side mount allows up to 8mm in space. Some 2.5" mechanical hard drives (not SSDs) that state 9mm are actually closer to 8mm thickness so you can just slide one in there as well.
Just a heads up- I have recently put my first prototype case on sale here. This case is the original one that uses 12mm cubes for the structure. It is in used condition but still very workable with mini ITX builds.
Also, I may also sell two of the frames shown in this post for an even lower price, just because of their imperfections, plus I don't have much use of them myself and are just taking up space. They might be of use of someone who wants to mod a cheap small case or just run an open air system.
I'm considering a slimmer version design of this case for HTPC and light gaming and workstation builds that supports only 1-slot cards. This case would also have internal power supply support and is 84mm wide, which is the same width as the In Win Chopin.
Things have been more quiet with the project, but just a small update with the inner frame. The front supporting piece is now moved inwards instead of projecting outwards like before.
In this update, the frame is able to support itself using fewer screws (2 each have been removed in the top and the bottom) but also now there's no need for counter sunk holes on those corners since the outer panel won't need them to sit flush anymore.
Now it's possible to use button head screws on the frame without them getting in the way of the front panel. It's a subtle change, but it will make assembly much easier.
It's been one month later and I'm posting another update to give you the status of this case project.
For now I've downsized to Ryzen APU build for my main rig to go even more compact but I will still consider a discrete GPU rig in the future. In the meantime, for this project I will be revising the case structure's design.
First, the side join pieces that run from front to back will be made of thicker aluminum, at least 5mm. This makes screwing side panels easier, and instead of using additional standoffs, which complicates the assembly process. It also means fewer panels- no longer will the top and bottom sides require dual layering. I found it better to use more single layer side with thicker join pieces, than dual layer with thinner join pieces. Fewer pieces overall will need to be cut for each case.
The motherboard tray will be split into two smaller parts for the purpose of making PSU installation easier. I previously had thought of the idea of a tray that slides upwards to insert the PSU, but I thought the locking mechanism to keep it in place would complicate the design too much.
Also I'm moving more of my workflow to Fusion 360 again for the design of the case.
No longer able to make another prototype, I may want to crowdfund it. But that's a situation if push comes to shove.